Refactor HTTP/3 request handling and improve performance

.gitignore

@@ -5,6 +5,7 @@ docs/_build
 gtest-parallel-logs
 report.xml
 build
+build-*
 secrets
 Testing
 *.pcap

include/anyhttp/file_handler.hpp

@@ -0,0 +1,23 @@
+#pragma once
+
+#include "anyhttp/server.hpp"
+
+#include <filesystem>
+#include <string>
+
+namespace anyhttp
+{
+
+// =================================================================================================
+
+/**
+ * Serve a single file from below \p root, mapped into memory with mmap(). The part of the request
+ * path below \p prefix is taken as the path relative to \p root; anything that would escape
+ * \p root ("..", a symlink pointing outside) is rejected with 404.
+ */
+awaitable<void> serve_file(server::Request request, server::Response response,
+                           std::filesystem::path root, std::string prefix);
+
+// =================================================================================================
+
+} // namespace anyhttp

include/anyhttp/server.hpp

@@ -21,6 +21,24 @@ struct Config
    std::string listen_address = "::";
    uint16_t port = 8080;
    bool use_strand = false;
+
+   //
+   // HTTP/3 only: how long a QUIC connection may go without a packet from its peer before it is
+   // dropped. This is the only way a peer that vanished without a CONNECTION_CLOSE -- a killed
+   // client, a machine that went to sleep -- is ever noticed, so it also bounds how long its
+   // session and streams stay around. 30s is what the ngtcp2 examples use.
+   //
+   std::chrono::nanoseconds idle_timeout = 30s;
+
+   //
+   // HTTP/3 only, testing aid: probability (0.0 ... 1.0) with which an individual QUIC datagram
+   // is thrown away instead of being processed (rx) or actually sent (tx). This exercises loss
+   // recovery -- retransmits, PTO, ACK handling -- without needing a lossy network. Dropping
+   // happens per QUIC packet, i.e. GRO-coalesced datagrams are dropped individually and TX
+   // GSO batching is bypassed while `drop_rate_tx` is non-zero.
+   //
+   double drop_rate_rx = 0.0;
+   double drop_rate_tx = 0.0;
 };
 
 // =================================================================================================
@@ -135,8 +153,7 @@ class Response
 
 // =================================================================================================
 
-using RequestHandler = std::function<void(Request, Response)>;
-using RequestHandlerCoro = std::function<asio::awaitable<void>(Request, Response)>;
+using RequestHandler = std::function<asio::awaitable<void>(Request, Response)>;
 
 class Server
 {
@@ -151,7 +168,6 @@ class Server
    executor_type get_executor() const noexcept;
 
    void setRequestHandler(RequestHandler&& handler);
-   void setRequestHandlerCoro(RequestHandlerCoro&& handler);
 
    asio::ip::tcp::endpoint local_endpoint() const;
 

include/anyhttp/server_impl.hpp

@@ -79,12 +79,7 @@ class Server::Impl : public std::enable_shared_from_this<Server::Impl>
    }
 
    void setRequestHandler(RequestHandler&& handler) { m_requestHandler = std::move(handler); }
-   void setRequestHandler(RequestHandlerCoro&& handler)
-   {
-      m_requestHandlerCoro = std::move(handler);
-   }
    const RequestHandler& requestHandler() const { return m_requestHandler; }
-   const RequestHandlerCoro& requestHandlerCoro() const { return m_requestHandlerCoro; }
 
    asio::awaitable<void> udp_receive_loop();
    int udp_on_read(Endpoint& ep);
@@ -110,7 +105,6 @@ class Server::Impl : public std::enable_shared_from_this<Server::Impl>
    std::unordered_map<std::string, std::shared_ptr<Http3Session>> m_quic_handlers;
 
    RequestHandler m_requestHandler;
-   RequestHandlerCoro m_requestHandlerCoro;
    bool m_stopped = false;
 };
 

src/beast_session.cpp

@@ -395,6 +395,7 @@ class ResponseWriter
       WriterBase<server::Response::Impl, Stream, http::response_serializer<http::buffer_body>>;
 
 public:
+   using super::logPrefix;
    using super::message;
    using super::serializer;
    using super::stream;
@@ -426,6 +427,10 @@ class ResponseWriter
       if (message.find(http::field::server) == message.end())
          message.set(http::field::server, "anyhttp");
 
+      mlogd("{} {}", message.result_int(), message.reason());
+      for (const auto& header : message)
+         mlogd("  \x1b[1;34m{}\x1b[0m: {}", header.name_string(), header.value());
+
       //
       // TODO: For bundling writing the header and body, we should just post the writing here,
       //       giving an async_write the chance to add a body to the message first.
@@ -716,7 +721,7 @@ awaitable<void> ServerSession<Stream>::do_session(Buffer&& buffer)
       //
       server::Request request_wrapper(std::move(reader));
       server::Response response_wrapper(std::move(writer));
-      if (auto& handler = server().requestHandlerCoro())
+      if (auto& handler = server().requestHandler())
       {
          try
          {